1. Field of the Invention
This invention relates to a contactor-circuit breaker housing firstly power poles which include moving contact bridges cooperating with fixed contact bridges, and an electromagnet serving to activate the moving contacts in contactor mode and comprising a fixed magnetic circuit, a moving magnetic circuit and a coil whose electric supply is controlled by a switch, and secondly at least one current sensor serving to control a releasing electromagnet.
2. Discussion of the Background
A contactor is used to cut off or to supply, in response to a control signal, the supply line of a load such as a motor. A circuit breaker is usually associated with the contactor, the purpose of which circuit breaker being to open the line if an overcurrent, due for example to a short-circuit, is detected. The circuit-breaker function is necessary in order to open the line quickly, for the opening of the contactor for the purpose of cutting off the supply to the electromagnet coil would take too long because of the slow decline of the current through the coil.
The contactor and circuit breaker functions are sometimes combined in a single electric switch appliance, referred to as contactor-circuit breaker, such as the appliance described in French patent FR2638563. A protection device, such as for example a striker, is thus associated with the contact bridge of the contactor, which device acts directly on the moving contact bridge so as to open the contacts in case of detection of a short-circuit current. This appliance also comprises a lock which receives orders from the (thermal and magnetic) protective device in order to act on the supply of the coil. However, such an appliance remains bulky and expensive.